Laboratory burner



Feb. 2, 1965 s. R. ROSENTHAL 3,168,640

LABORATORY BURNER Filed Nov. 15, 1962 2 Sheets-Sheet l INVENTOR.

50L R0) ROSENTHAL BY Feb. 2, 1965 s. R. ROSENTHAL 3,168,640

LABORATORY BURNER Filed NOV. 13, 1962 FIG 4 2 Sheets-Sheet 2 INVENTOR. SOL R0) ROSENTHAL BY M154 & X

ATTYS United States Patent Ofiice 3,168,644) LABORAEGRY EURNER Sol Roy Rosenthal, 230 E. Delaware Place, Chicago 11, Ill. Filed Nov. 13, 1962, Ser. No. 236,852 18 Qlaims. (Cl. 219-242) This invention relates to a burner of the laboratory type adapted for use in scientific, analytical, medical, dental and similar types of work. More particularly, the burner embodies a heating element that is accessible for heating a material or object held by the user and yet is enclosed to protect the user and the surrounding area. The burner also enables the user to view the material or object being subjected to heat and the results of heating.

In various laboratory type procedures, materials and objects are heated to burn, incinerate, melt, vaporize, or sterilize them. Frequently, it is necessary or desirable to hold or manipulate the materials or objects while keeping the process of heating under direct observation. Examples of the procedures includes incineration of materials for analytical purposes, flame tests, sterilization of instruments and the like, and melting or softening of materials such as wax and gutta percha, to name but a few. Such procedures are conducted widely by doctors, dentists, chemists, bacteriologists, technicians and others.

When it is desired to view the heating process, the individual should be protected from harm due to spattering, dripping, and other results of heating and decomposition, and it is desirable also to protect the surrounding area. Glass shields or enclosed compartments are frequently used to provide such protection, and safety glasses are worn. However, the protective measures are difficult to provide or inconvenient in many situations, and those measures actually taken may be inadequate.

An important object of the invention, therefore, is to provide a laboratory burner or the like which is accessible for heating materials and objects held by the user and which enables the user to conduct and view the heating process safely while also protecting the surrounding area. More particularly, it is an object to provide a very simple, compact, and versatile spatterproof visual burner which may be employed in almost any desired location.

Another object is to provide a burner accomplishing the foregoing objects and which is adapted to subject materials and objects to localized high temperatures.

An additional object is to provide a portable laboratory burner accomplishing the foregoing objects, and particularly, which may be placed in a convenient location on a workbench, table, or stand. In one embodiment of an electrical burner according to the invention, the burner may be plugged into a convenient electrical outlet.

A further object of the invention is to provide a burner which may be employed in various positions as most convenient, and particularly, which may be horizontally or vertically disposed.

Another object is to provide a burner which is adapted to be kept clean and functioning properly, and from which residues are easily removed.

These and other objects, advantages and functions of the invention will be apparent on reference to the speciiication and to the attached drawings illustrating preferred embodiments of the invention, wherein like parts are identified by like reference symbols in each of the views and wherein:

FIGURE 1 is a side elevational view of one embodimerit of an electrical burner;

FIG. 2 is an end elevational view thereof;

FIG. 3 is a top plan View thereof, with the mantle thereof removed;

PEG. 4 is an enlarged fragmentary vertical sectional 3,l5,ti l9 Patented Feb. 2, 1955 view of the heating element and the base of the burner;

FIG. 5 is a perspective view of another embodiment of an electrical burner;

FIG. 6 is an enlarged elevational view with parts broken away and in section of a stand which may be employed with heating elements such as illustrated in the preceding Views; and

FIG. 7 is a perspective view of a gas burner.

The invention provides a laboratory burner which includes a heating element, and a heat-resistant transparent iantle around the element and having an access opening, whereby an instrument may be inserted in the mantle adjacent to the heating element.

Referring to FIGS. 1-4 of the drawings, a preferred portable electrical burner is generally indicated by the number it). The burner includes a heating element 12 having a heating section 13. The heating element is an electrical resistance heating rod of a conventional type, which is adapted for reaching temperatures up to 1500 F. A mantle or hood 14 is mounted on the heating section in a substantially horizontal position, and it encloses the heating section. The mantle includes a heat-resistant transparent cylindrical tubular wall 15 and circular openings 17 and 19 at the opposite ends thereof. Preferably, the mantle is a glass tube constructed to withstand such temperatures, in particular, having an extremely low coeflicient of thermal expansion. It may be fabricated from high silica glass, for example, 96% silica glass identified as Vycor.

As seen in FIG. 4, the illustrative heating element 12 is a unitary electrical heating rod of the sheathed resistance conductor type. It includes an elongated outer tubular metal sheath 16, an electrical conductor 18, and a highly compacted mass of heat conducting and electrically insulating material 26 that may essentially comprise magnesia. The conductor is embedded in the compacted mass and spaced thereby from the sheath. A helical resistance conductor 22 is embedded in the mass 20 and joined to the conductor 18 in the heating section 13 of the element.

As seen in F163. 2 and 3, the rod is bent upon itself in forming the heating element 12, to provide two arms 24 and 26. Referring again to FIG. 4, the conductor 18 extends beyond the sheath 16 at the opposite ends of the rod, on one end 28 of each arm, to provide a projecting electrical terminal 30. Each end is closed by a vitreous seal 32, in the form of a cellular and porous ceramic body. The construction of the heating element so far described has been disclosed previously in U.S. Patent No. 2,962,684. A prong 34 is joined to or in tegral with each terminal 39.

The heating element arms 24 and 26 include respective spaced parallel horizontal heater arm sections 36 and 38. The sections are joined or bridged by a semicircular laterally upwardly extending or vertical heater arch section 40 having the same internal construction. The arms and arch sections together constitute the heating section 13. It will be evident that the loop 40 may be formed by making a reverse bend in a heating rod, and bending the closed end of the bent rod at right angles to the main body of the rod, providing bends 42 at the junctures of the arm sections 36 and 38 with the arch 40. The arm and arch sections form a supporting frame for the mantle 14, as subsequently described.

As seen in FIG. 1, the heating element arms 24 and 26 are turned downwardly at the ends of the arm sections 36 and 38 opposite the arch, forming 90 bends 44. The sections of the arms below the bends serve as supports for the heater sections. The arms are again bent a short distance beyond the bends, just below the mantle saeaeso 14, at obtuse angle bends 46 in the reverse direction. Upright stop sections 45 are formed between the bends 44 and 46. Referring also to FIGS. 2 and 3, the arms re brought closer together shortly beyond the reverse bends ie, by inwardly directed obtuse angle bends 43. The arms shortly therebeyond'are caused to extend in parallel sections 51 by oppositely directed obtuse angle bends t T e arms are directed downwardly vertically at the ends of the sections 51 by obtuse angle bends 52 approximately at the center of the burner it.

The heating element arms 24 and 26 are joined at their lower ends 28, i.e., at the opposite ends of the heating rod 12, by a base element or disk 54-. The prongs 34 extend from the underside of the base element for insertion into a suitable 31 -ale electrical outlet, and the base element provides support for the burner thereon. The base element is constructed of dielectric plastic or ceramic material. An opening or chamber 56 (FIG. 4) is provided in the base element, and breather openings 58 and 69 (see also FIGS. 1 and 2) extend therefrom to the outer surface of the element. he openings accommodate breathing through the heating element seal 32, as described in the above-identified patent, and serve to dissipate any heat which may be conducted to the base by the sheath in.

The high temperatures are reached in the heater sections 36 and 3% of the arms and in the arch section 4% joining their outer ends. A certain amount of heat is conducted from the heater sections by the sheath l6. Depending upon the temperature reached, means may be provided for dissipating heat conducted away from the mantle 14. In the illustrative embodiment, four conductive fins 62 of relatively large surface area are joined to the parallel sections 51 of the arms 24 and 26, between the mantle and the lower ends of the arms. The fins have openings bordered by sleeves 64, which receive and are secured to the arms.

The heater sections 36 and 38 of the arms extend in parallel at a distance from each other such that the width of the heating element at the heating section 13 is approximately the same as the inside diameter of the mantle 14. The radius of curvature of the outer periphery of the arch id is approximately the same as the inside radius of the mantle and the radius of the end openings 17 and 19. The burner is assembled by sliding the mantle on the heating element from the arched outer end thereof until the mantle substantially reaches the stop sections 45, which limit movement of and locate the mantle. The mantle substantially completely encloses the heater arm sections 36 and 38 and the heater arch 4G; with the latter located in the mantle a short distance from its outer end and proximate to the end opening 17 thereat. The heater arm and arch sections thus form a frame which supports the mantle horizontally. The outer end opening 17 serves 'as an access opening for the insertion of an instrument from the side of the burner in the mantle and adjacent to the heating element.

As an example of a prefered size for the laboratory burner ll), its overall height from the bottom of the base element 54- may be about 4 inches. The mantle 14 may be about 3 inches in length and constructed of 30 mm. 0.13. glass tubing. It will be evident that the burner is extremely compact and convenient, and at the same time, exceptionally functional.

To exemplify the manner in which the burner may be used, the chemist may place a quantity of a substance on a suitable instrument and insert it in the mantle and adjacent to the arch section 49 or the arm sections 36 and 38. The arch also serves to permit the introduction of an instrument for any desired distance without interference by the heating element. The mantle serves to concentrate and localize the heat in the manner of an oven, and the interior is substantially uninfiuenced by external atmospheric conditions. Burning or melting of solids, vaporization of liquids, and other procedures are accomplished without interference, while the operations are kept under direct observation. The progress of the operations may be followed, and the colors produced can be observed through the transparent wall 15, as in the case of a dame test. Sputtering and the like is confined within the mantle, and the dangers thereof are obviated. Gases and vapors are confined, and their escape is limited to the ends of the mantle. Materials wmch may drop from the instrument fall between the arm sections 36 and 38 and are collected at the bottom of the wall 15. They may be removed subsequently, by brushing out loose materials or by simply removing and cleaning the mantle.

Similarly, probes, loops, stabs and spatulas may be sterilized by insertion within the burner. In making biological and bacteriological transfers and the like, such as with an instrument 68 having an innoculating loop 69 as illustrated in FIG. 7, the loop is inserted within the burner. At the same time, the mouth of a test tube or ilask may be sterilized by holding it against the outer surface of the Wall 15 of the mantle, which may be at a high temperature sufficient to sterilize the mouth.

FIG. 5 illustrates another embodiment of a portable electrical laboratory burner '70 which is especially suited for dental work. In this construction, a mantle 72 having the previously described cylindrical tubular glass construction is supported in substantially vertical position by a heating element 74. The heating element includes two arms 76 and '78 having their terminal ends secured to a base element 54 of the previously described construction. The arms extend upwardly in the vertical direction from the base element. The arms are bent horizontally at 'points spaced above the base, to form two elbow sections 8% which support the mantle on ledges formed thereby. The arms are turned upwardly a short distance beyond the elbows, at bends 32, and they extend vertically thereabove. The upper portions of the arms provide two spaced parallel vertical heater arm sections 84 and 86 connected at their outer or upper ends by a horizontal heater arch section 83. The heater arm and arch sections include a resistance heating coil or the like such as indicated at 22 in FIG. 4, for producing hi h temperatures thereat.

The mantle '72 is supported vertically by the arm sections 34 and 86 and the arch section 88 acting as a supporting frame, with the mantle resting on the elbow sections 8b. The arm sections 84 and as are disposed to one side of the vertical axis of the mantle, and the mantle ex- I tends horizontally beyond the base element 54. This construction provides for heating substances which have a tendency to fall from the instrument, such as Wax and gutta percha, as illustrated on the instrument gtl shown with the burner. The Wax may be allowed to fall on the surrounding surface 92 of a workbench or the like, or a waste collector may be situated on the surface beneath the mantle. This embodiment is illustrated as being plugged into a female outlet 94 which is provided on such a Workbench.

As an item of dental equipment or the like, the burner '79 need develop only temperatures in a lower range of about 500 to 900 F. The size of the unit may be coir-- parable to that of the preceding embodiment. In using the burner, the instrument 96 is inserted from above the burner, in the access opening 96 at the upper end of the mantle, and adjacent to the arch 83 or the arm sections 84 and 86. If desired, the arch may be employed as a rest or stop for the instrument, to support it temporarily.

Heating elements such as illustrated in FIGS. 14 and FIG. 5 may be detachably mounted on a portable stand or base 150, as illustrated in FIG. 6. The stand includes a body 192, a bottom closure 1%, a pair of element holders 1%, and a securing ring 1%. A terminal block 11 3 of dielectric material such as plastic or ceramic material is mounted on the bottom closure within the body, and a pair of spring contacts 112 are mounted thereon and separated thereby. An electrical conductor 114 is joined to the stand, for connection to a source of electrical power. The other end of the conductor may be joined to a male electrical plug (not shown) in conventional manner, for insertion in an electrical outlet. The conductor is electrically connected to a conventional switch 116 mounted on the stand, which may be of the transformer or rheostat type. The switch is in turn connected to the contacts 112.

The arms 118 and 120 of a heating element such as previously illustrated are mounted on the stand 100 at their terminal ends. In this construction, the conductors 13 shown in FIG. 4- may continue beyond the sheaths 16 to provide terminals which are received by the spring contacts in conductive relation. The arms are securely mounted on the stand by means of the holders 186, which are semicircular clamps receiving the arms therebetween and joined together by a screw 122. The holders are seated on an inwardly extending shoulder 124 of the body 1ti2. An externally threaded circular ridge 128 is integral with the shoulder and extends upwardly therefrom around the holders 1%. The securing ring 163 is internally threaded for engagin the ridge, and it extends i wardly therearound to engage a shoulder 128 formed on each holder. The ring is turned into threaded engagement with the ridge 128 while bearing on the shoulder 128, to secure the holders and thereby the heating element arms 118 and 120 on the stand.

The electrical construction of the burner has certain advantages over other types of burners. In some locations, it is difficult or impractical to supply fuel gas for such purposes. Gas burners are alfected to a greater extent by atmospheric conditions, and the usual hazards attend their use. The electrical burners may be used over a wide temperature range and may be controlled accurately. Heating is uniform without cold areas, and there is no gas pressure.

In certain situations, it is, nevertheless, desirable to provide a gas burner. FIG. 7 illustrates a portable burner 129 of this type constituting a preferred embodiment of the invention. The burner includes a horizontally disposed heat-resistant transparent cylindrical tubular mantle 13% like those of the preceding embodiments, preferably -a glass tube resistant to high temperatures. The heating element constitutes a gas burner tube. It includes two spaced parallel horizontal heater arm sections 132 and 13 connected at outer ends thereof by a semicircular vertical heater arch section 136.

The dispositions of the arm and arch sections are essentially like those of the electrical element sections 36, 33 and 40 of FIGS. 1-4, to provide a like supporting frame for the mantle. Each of the arm sections 132 and 13d and the arch section 136 is provided with a plurality of gas jet openings 138 spaced therealong. The openings are directed inwardly towards the horizontal axis of the mantle, to produce a concentrated heating zone in the center of the mantle. The openings in the arch section are directed substantially in a vertical plane, and the openings in the arm sections are directed substantially in a horizontal plane. With the openings thus disposed, the likelihood that they will be fouled with material being heated therein is minimized. It will be apparent that the dispositions of the openings may be varied, and if desired, jet nozzles may be provided in the openings.

The heater element arm sections 132 and 134 may be mounted at their inner ends on a portable burner stand 14d of generally conventional construction. The stand may include a base 142, a valved gas inlet fitting 144, and a tubular column 14-6 having an air inlet opening 147 at its lower end and a closed upper end. The arm sections 132 and 134 are mounted at the upper end of the column in communication with the interior thereof. A gas inlet tube 148 is joined to the inlet fitting, and it is adapted for securing a flexible conduit 150 such as a rubber tube thereto, for connecting the burner to a source of combustible gas. A thumb piece 152 is employed for regulating the supply of gas, by means of a valve (not shown) within the inlet fitting. A tubular sleeve 154 is rotatably mounted on the column 146. The sleeve is provided with an air inlet opening 156 which is arranged to register with the air inlet opening 147 in the column and is rotatable with respect thereto, to regulate the quantity of air entering and mixing with the gas in the column.

The gas burner 129 is used in much the same manner as the electrical burner illustrated in FIGS. l-4. The instrument 68 is inserted in an access opening 158 at the outer end of the mantle 130. As heating takes place, the process may be observed through the transparent mantle. The user is protected from spattering, and escape of combustion gases is confined to the ends of the mantle. Material which drops off of the instrument collects at the bottom of the mantle and subsequently may be removed conveniently.

The gas burner provides a highly concentrated gas heating chamber. Interference with the heating process and with the operation of the burner due to conditions in the surrounding atmosphere is substantially prevented.

The invention thus provides a very useful laboratory burner which accomplishes the above objects. While there have been shown and described several preferred embodiments of the invention, it will be apparent that various changes and modifications may be made in the construction and arrangement thereof within the spirit and scope of the invention. It is intended that such changes and modifications be included within the scope of the appended claims.

I claim:

1. A spatterproof visual laboratory burner or the like producing concentrated high temperatures which comprises a heating element including a heater arm section, and a heat-resistant transparent mantle enclosing said arm section and supported thereby, said mantle including a tubular wall and said arm section being disposed against said wall and extending therealong for substantially the entire length of the wall for supporting the wall and for directing heat inwardly from the wall towards the center of the mantle to produce concentrated high temperatures in the center of the mantle, said mantle having an access opening leading to the center thereof whereby an instrument may be inserted in the center thereof adjacent to said arm section.

2. A burner as efined in claim 1 wherein said heater arm section comprises an electrical resistance heating rod.

3. A burner as defined in claim 1 wherein said heater arm section comprises a gas burner tube having a plurality of gas jet openings therealong.

4. A spatterproof visual laboratory burner or the like producing concentrated high temperatures which comprises a heating element including a pair of heater arm sections, and a heat-resistant transparent tubular mantle enclosing said arm sections and supported thereby, said mantle including a tubular wall and said arm sections being disposed against the wall therealong for supporting the Wall and for directing heat inwardly from the wall towards the center of the mantle to produce concentrated high temperatures in the center of the mantle, said mantle having an access opening adjacent to outer ends of said arm sections leading to the center of the mantle, whereby an instrument may be inserted in the center of said mantle adjacent to said arm sections.

5. A burner as defined in claim 4 wherein said heater arm sections are joined by a laterally extending heater arch at said outer ends thereof, and said mantle wall lies on said arch.

6. A burner as defined in claim 4 wherein said mantle is a high tern erature-resistant glass tube.

7. A burner as defined in claim 4 wherein said heater grease-s H arm sections and mantle extend horizontally for inserting an instrument from one side of the burner.

8. A burner as defined in claim 4 wherein said heater arm sections and mantle extend vertically for inserting an instrument from above the burner.

9. Aspatterproof visual laboratory burner or the like producing concentrated high temperatures which comprises an electrical resistance heating rod including a heater arm section, and a high temperature resistant transparent glass tube enclosing said arm section, said arm section being disposed adjacent the tube wall and extending therealong for substantially the entire length of the wall for directing heat inwardly from the wall towards the center of the tube to produce concentrated high temperatures in the center of the tube, said tube having an access opening leading to the center thereof whereby an instrument may be inserted in the center thereof adjacent to said arm section.

10. A spatterproof visual laboratory burner or the like producing concentrated high temperatures which comprises an electrical resistance heating element including a pair of spaced parallel heater rod arm sections, and a high temperature-resistant transparent glass tube enclosing said arm sections and supported thereby, said arm sections being disposed against the tube wall therealong for supporting the wall and for directing heat inwardly from the wall towards the center of the tube to produce concentrated high temperatures in the center of the tube, said tube having an access opening adjacent to outer ends of said arm sections leading to the center of the tube, whereby an instrument may be-inserted in the center of said tube adjacent to said sections.

11. A spatterproof visual laboratory burner or the like producing concentrated high temperatures which comprises a gas burner heating element including a pair of spaced parallel heater tube arm sections having a plurality of gas jet openings therealong, and a high temperature-resistant transparent glass tube enclosing said arm sections and supported thereby, said arm sections being disposed against the tube wall therealong for supporting the wall and for directing heat inwardly from the wall towards the center of the tube to produce concentrated high temperatures in the center of the tube, said tube having an access opening adjacent to outer ends of said arm sections, leading to the center of the tube, whereby an instrument may be inserted in the center of said tube adjacent to said arm sections.

12. A portable spatterproof visual laboratory burner or the like producing concentrated high temperatures which comprises an electrical resistance heating rod including a pair of spaced parallel heater arm sections, the opposite ends of said rod being adapted for plugging into an electrical outlet, and a high temperature-resistant transparent glass tube enclosing said arm sections, said arm sections being disposed adjacent the tube wall therealong for directing heat inwardly from the wall towards the center of the tube to produce concentrated high temperatures in the center of the tube, said tube having an access opening leading to the center thereof whereby an instrument may be inserted in the center thereof adjacent to said arm sections.

13. A burner as defined in claim 12 and including a base element connecting said rod ends and providing support for the burner.

14. A burner as defined in claim 12 and including heat dissipating elements on said rod between said tube and said rod ends.

15. A portable spatterproof visual laboratory burner or the like producing concentrated high temperatures which comprises a portable stand, an electrical conductor joined to said stand for connection to a source of electrical power, a pair of electrical resistance heating rod arms including a heater section adjacent one end of each, the remaining end of each arm being mounted on said stand and electrically connected to said conductor, and a hightemperature resistant transparent glass tube enclosing said heater sections, said heater sections being disposed adjacent the tube wall therealong for directing heat inwardly from the wall towards the center of the tube to produce concentrated high temperatures in the center of'the tube, said tube having an access opening adjacent to said first-named ends of said arms leading to the center of the tube, whereby an instrument may be inserted in the center of said tube adjacent to said heater sections.

16. A portable spatterproof visual laboratory burner or the like producing concentrated high temperatures which comprises a portable stand, means for connecting said stand to a source of combustible gas, a pair of gas burner tube arms including a heater section adjacent one end of each having a plurality of gas jet openings therealong, the remaining end of each arm being mounted on said stand and comunicating with said connecting means, and a heat-resistant transparent tubular mantle enclosing said heater sections and supported thereby, said mantle including a tubular wall and said heater sections being disposed against the tube wall therealong for supporting the wall and for directing heat inwardly from the wall towards the center of the mantle to produce concentrated high temperatures in the center of the mantle, said mantle having an access opening adjacent to said first-named ends of said arms leading to the center of the mantle, whereby an instrument may be inserted in the center of said mantle adjacent to said heater sections.

17. A spatterproof visual burner or the like producing concentrated high temperatures which comprises an electrical resistance heating rod having a heater section at one end thereof and a pair of terminals for connection to an electrical power source at the opposite end thereof, and a high temperature-resistant transparent glass tube mounted on said heater section and closely enclosing the section to thereby provide an enclosed concentrated high temperature zone in said tube visible from the outer side, said rod constituting the sole support for sm'd tube, said tube being open at both ends whereby the tube may he slid on and off of said heater section and an instrument may be inserted into said high temperature zone from an end of the tube when the burner is assembled.

18. A spatterproof visual burner or the like producing concentrated high temperatures which comprises a heating element having a horizontally extending heater sec-' tion at one end thereof, and a horizontally extending high temperature-resistant transparent glass tube mounted on said heater section and closely enclosing the section to thereby provide an enclosed concentrated high temperature zone in said tube visible from the outer side, said heater section constituting the sole support for said tube, said tube being open at both ends whereby the tube may he slid on and oil of said heater section and an instrument may be inserted into said high temperature zone from an'end of the tube when the burner is assembled.

References Qited in the file of this patent UNITED STATES PATENTS 

1. A SPATTERPROOF VISUAL LABORATORY BURNER OR THE LIKE PRODUCING CONCENTRATED HIGH TEMPERATURES WHICH COMPRISES A HEATING ELEMENT INCLUDING A HEATER ARM SECTION, AND A HEAT-RESISTANT TRANSPARENT MANTLE ENCLOSING SAID ARM SECTION AND SUPPORTED THEREBY, SAID MANTLE INCLUDING A TUBULAR WALL AND SAID ARM SECTION BEING DISPOSED AGAINST SAID WALL AND EXTENDING THEREALONG FOR SUBSTANTIALLY THE ENTIRE LENGTH OF THE WALL FOR SUPPORTING THE WALL AND FOR DIRECTING HEAT INWARDLY FROM THE WALL TOWARDS THE CENTER OF THE MANTLE TO PRODUCE CONCENTRATED HIGH TEMPERATURES IN THE CENTER OF THE MANTLE, SAID MANTLE HAVING AN ACCESS 